Efficient encoding/decoding apparatus

Details Efficient encoding/decoding apparatus Efficient encoding/decoding apparatus

1995-05-02

1997-02-18

Gaffin, Jeffrey A.

Coded data generation or conversion

Digital code to digital code converters

364745, H03M 700

Patent

active

056044941

DESCRIPTION:

BRIEF SUMMARY
TECHNICAL FIELD

This invention relates to an efficient encoding/decoding apparatus, and more particularly to such an efficient encoding/decoding apparatus capable of suppressing accumulation (storage) of errors in repeatedly encoding/decoding digital signals, e.g., video signals, etc.


BACKGROUND ART

In recent years, as an efficient encoding/decoding apparatus adapted for compression-encoding a digital signal thereafter to decode such encoded signal, there have appeared such digital VTRs adapted to compression-encode, e.g., a digital video signal to record such encoded signal onto a recording medium to decode a signal reproduced from the recording medium.
In the above-mentioned VTRs, a procedure as described below is generally employed to compress a video signal to record the compressed signal to further reproduce the recorded signal to expand it.
Namely, although not shown, digital video data on the time axis delivered to signal recording system (encoding side) is first caused to undergo orthogonal transform processing, e.g., Discrete Cosine Transform (DCT), etc. so that such data is transformed into data on the frequency axis. The video data on the frequency axis is quantized and is further caused to undergo, e.g., variable length encoding, etc. so that such data is compressed. The compressed video data is recorded onto a magnetic tape as a recording medium.
Moreover, at signal reproducing system (decoding side), the compressed video data recorded on the recording medium is reproduced. This reproduced data is expanded by variable length decoding, and is further caused to undergo inverse quantization. The inversely quantized data is caused to undergo Inverse Discrete Cosine Transform (IDCT) as inverse orthogonal transform so that the video data on the frequency axis is restored into video data on the time axis for a second time. Thereafter, such restored video data will be taken out.
As digital VTR for carrying out compression-encoding of such video signal, there are, e.g., digital VTRs using, e.g., predictive encoding system between frames/between fields. In such digital VTR, it is necessary to allow local decode picture for carrying out the predictive encoding at the encoding side and decode picture of the decoding side to be in correspondence with each other. At this time, there is the problem that if operation methods at inverse transform (inverse orthogonal transform) in local decoding at the encoding side and inverse transform (inverse orthogonal transform) at the decoding side and rounding methods at the encoding side and the decoding side are different, miss match which will be described later may take place. For this reason, in the recommendation H.261 (Television conference/telephone low speed moving picture encoding algorithm) in Comite Consultatif Internationale Telegraphique et Telephonique (CCITT), quantization representative values are caused to be odd number as shown in Table 1.


TABLE 1 __________________________________________________________________________ QUANTIZATION REPRESENTATIVE VALUE OF QUANTIZATION WITH DEAD ZONE QUANT 1 2 3 4 . 8 9 . 17 18 . 30 31 .backslash. QUANTIZATION INDEX __________________________________________________________________________ -127 -255 -509 -765 -1019 . -2039 -2048 . -2048 -2048 . -2048 -2048 -126 -253 -505 -759 -1011 . -2023 -2048 . -2048 -2048 . -2048 -2048 . . . . . . . . . . . . . . -2 -5 -9 -15 -19 . -39 -45 . -85 -89 . -149 -155 -1 -3 -5 -9 -11 . -23 -27 . -51 -53 . -89 -93 0 0 0 0 0 . 0 0 . 0 0 . 0 0 1 3 5 9 11 . 23 27 . 51 53 . 89 93 2 5 9 15 19 . 39 45 . 85 89 . 149 155 3 7 13 21 27 . 55 63 . 119 125 . 209 217 4 9 17 27 35 . 71 81 . 153 161 . 269 279 5 11 21 33 43 . 87 99 . 187 197 . 329 341 . . . . . . . . . . . . . . 56 113 225 339 451 . 903 1017 . 1921 2033 . 2047 2047 57 115 229 345 459 . 919 1035 . 1955 2047 . 2047 2047 58 117 233 351 467 . 935 1053

REFERENCES:
patent: 5014134 (1991-05-01), Lawton et al.
patent: 5379356 (1995-01-01), Purcell et al.
patent: 5481553 (1996-01-01), Suzuki et al.

Affiliated with

Also associated with

Rating

Efficient encoding/decoding apparatus does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Efficient encoding/decoding apparatus, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Efficient encoding/decoding apparatus will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-1604946